Philosophy and Cognitive Science

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Philosophy and Cognitive Science

• Conceptual Role Semantics
• Joe Lau
• Philosophy
• HKU

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Readings

• Robert Cummins
• Excerpts on reserve at main office.
• Ned Block
• Online article.
• Advertisement for a theory of semantics, on
  reserve.

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Topic

• Some closely related theories
• Conceptual role semantics (CRS)
• Computational role semantics
• Functional role semantics
• Procedural semantics

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Three questions about a representational system

• Which are the representations?
• What do the representations mean?
• What makes a representation mean what it does?

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Q1 Identifying representations

• Which physical properties / states / objects are
  used to encode information / carry meaning?
• Which are the symbols?
• Information encoded by single neuron in the
  brain, or groups of neurons? In what form?
• Structured? Pictorial? Linguistic?

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Q2 What do they mean?

• Identifying their content / what the symbols
  represent.
• insalata means salad in Spanish.
• The firing of this neuron represents the boundary
  of a surface.

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Q3 theory of meaning

• Questions that remains even after the meaning of
  a representation is known.
• Given that X means Y, what explains the fact that
  X means Y?
• What is it for something to have a particular
  meaning?

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Comparing Q2 and Q3

• Q2
• Specifically about a system of representation.
• An empirical question to be resolved by empirical
  investigations.

• Q3
• A general question about the nature of meaning.
• A philosophical question about how the concept of
  representation is to be understood.

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CRS

• A theory of meaning that proposes an answer to
  the third question.
• Better a very rough and incomplete framework
  for answering the third question.

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Intrinsic vs. relational properties

• An intrinsic property of X a property that
  depends only on those properties internal to X.
• Example the mass of an object
• A relational property of X a property of X that
  depends on objects that exist externally of X.
• Example being a father

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Meaning as a relational property

• Being meaningful, having a particular meaning are
  relational properties of representations.
• The intrinsic properties of a physical object is
  not enough to determine its meaning.
• The meaning of a representation can change
  without changing its intrinsic properties.

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A unitary theory?

• Is there one single theory of meaning that
  applies to
• meaningful expressions in natural languages
• meaningful mental representations

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Meaning as covariation

• The meaning of a mental representation X depends
  on what X covaries with.
• X covaries with Y X causally correlates with Y

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Example

• Hubel and Wiesel orientation selectivity in the
  primary visual cortex (area V1)
• Activity of cells represent the presence of bars
  or boundaries at a certain orientation.

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Criticism

• At best works for detector representations
  that indicate proximate stimulus.
• Still such representations might covary with
  lots of things.
• But not the higher cognitive representations.
• Inaccurate covariation
• Non-existent covariation

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Functional role semantics

• Functionalism Mental states are defined by
  their functional role.
• Role vs. occupant
• Intentional mental states are defined by (a) type
  (e.g. belief) and (b) content (e.g. that snow is
  white)
• So the content of intentional mental states are
  defined and explained by their functional role.

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Functional role ???

• A relational property role within the functional
  organization of the mind
• Conceptual role semantics (CRS)
• Content defined by the role of a representation
  in cognition, e.g. reasoning, decision,
  perception, memory.

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Example

• Consider these inferential transitions between
  the beliefs of an agent
• PQ ? P
• PQ ? Q
• P, Q ? PQ
• Interpretation represents conjunction
  (and).
• Meaning determined by role in reasoning.

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Advantages of CRS

• Explain differences in meaning despite sameness
  of reference.
• Lee I have a lot of money.
• Lee Lee has a lot of money.

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Computational-RS

• CompRS CRS Computationalism
• Computionalism cognition is explained by
  computations.
• Mental content defined by conceptual role ?
  Mental content defined by computational role
  (role of representation in the minds program)

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CRS and FRS

• CRS is one version of FRS
• CRS is true ? FRS is true
• FRS is true not ? FRS is true
• There might be aspects of functional role which
  are not computational.
• e.g. role in interacting with some
  non-computational system.

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CRS and covariation

• Internal conceptual role might not determine all
  aspects of meaning.
• External causal connections have a role in
  determining which particular object a
  representation is about.

Tung-1
Tung-2
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Two factor CRS

• Which is more important? Internal or external
  factor
• Is this plausible?
• Internal factor imposes constraints on what the
  representation can be about
• External factor determines which particular
  object or property is represented.
• But perhaps some content is determined entirely
  by the internal factor (e.g. and).

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Narrow vs. wide content

• Narrow content content that depends only on
  what is inside the head.
• Wide content content that depends also on
  objects outside the head.